1. Field of the Invention
The present invention relates generally to the field of orthopedic casts and splints used to immobilize a body part, and more particularly to a unitary preformed multilayer casting or splinting device and method of forming such.
2. Description of the Related Art
In the older art, casting typically required multiple steps: covering that part of the body to be immobilized with padding and a waterproof layer, soaking strips of casting material and applying them to the body over the above layers, smoothing the surfaces, and allowing it to dry and cure. The same process was used for splints, but part of the finished cast was cut away after forming to make the splint (as described in Gruber). This process required stocking padding, waterproofing, casting resin or plaster of paris, etc., and was time consuming, messy and required some skill and training.
To overcome these problems, various unitary products have been devised, as illustrated in the above listed patents. Several of these (Gaylord, Parker '299 and Parker '738) use stockinette or tubular material to enclose the casting material. The problem with a tubular sheath, is that it restricts the width of the device to that of the sheath. Inserting the inner layer(s) into a sheath can be difficult, and if various widths are to be used, one must obtain and keep an inventory of various sizes of sheathing material. Further, such tubular sheathing presents the same material on all sides of the device, so that the patient side and the non-patient side are covered with the same material. Finally, the use of tubular sheathing precludes the formation of a variable outline of the device, i.e., wedge-shape, curved sides, serpiginous shapes, "T" shapes, "V" shapes, "H" shapes, and the like. A further disadvantage of using the same material, either as a sheath or internally, on both sides of the device, is that if the material is padding (as in Parker '299), it unnecessarily increases the thickness, bulk and cost of the device, since padding is only needed on the patient side of the device.
Further problems with some unitary casting devices is that the patient contact surface is waterproof. This allows moisture to build up under the cast or splint and can cause skin damage or infection. Other devices have attempted to solve this problem by making the patient contact surface out of fabric that absorbs moisture or is hydrophilic. This can cause excess moisture to be absorbed and held against the patient's skin.
Yet another disadvantage of some devices, is that the various layers of the device are made of material that not only allows water to pass freely through the layer(s), but are also hydrophilic (such as fabric stockinette, and the like); this causes retention of excess moisture when the device is wetted prior to use, such that the device must be wrung out, and results in prolonged drying times.
Once the unitary product is made, it is usually sealed in a waterproof container, such as foil or plastic, to keep the resin or casting material from getting moist and setting prematurely. If the casting material used is plaster of paris, sealing is less important than with synthetic resin casting material.